SpaceX makes a successful return to flight

The Falcon 9 rocket for Saturday's Iridium NEXT launch is shown on the pad Friday morning.

SpaceX

Post-launch update:
Despite some last minute concerns about strong winds and a wayward
boat, SpaceX launched on Saturday morning from Vandenberg Air Force
Base. The Falcon 9 rocket made a picturesque ascent, delivering its
payload of 10 large satellites into low-Earth orbit (they should reach
their final 625km orbit about 90 minutes after launch). The first stage
then descended back to Earth and, for the first time, an on board camera
provided views all the way down.

The rocket then stuck its landing on Just Read the Instructions, marking the first time the company has landed a booster in the Pacific Ocean.

Original story: Today SpaceX will attempt to launch its Falcon 9 rocket for the first time since a fueling accident
on Sept. 1, 2016, which destroyed the booster and its satellite payload
on the launch pad. The instantaneous launch window for Saturday's
attempt opens at 12:54pm ET (17:54pm UK), with liftoff occurring
from Space Launch Complex 4E at Vandenberg Air Force Base in California.

After a rather quick investigation
into the September accident, in which SpaceX concluded that one of
three composite overwrapped pressure vessels inside the rocket's second
stage liquid oxygen tank failed, the company has modified the fueling
process. By taking a slower approach with its load and go fueling
method, SpaceX expects to put less stress on the pressure vessels.

During SpaceX's last successful mission,
the launch of JCSAT-16 in August, fueling of kerosene and liquid oxygen
both began 35 minutes before launch. Now the company says kerosene
loading will begin 70 minutes before launch, with liquid oxygen fueling
beginning at 45 minutes prior.

Saturday's launch will boost 10 Iridium NEXT
satellites to a 625-km orbit. These are the first 10 of 70 next
generation satellites that SpaceX will launch for Iridium and its mobile
voice and data satellite communications network. After boosting the
satellites into space, the first stage of Falcon 9 will attempt a
landing on the Just Read the Instructions droneship in the Pacific Ocean. The webcast should begin about 20 minutes before Saturday's launch window opens.

Public webcast of SpaceX return to flight launch.

The launch attempt comes at a critical time
for SpaceX, which has had two accidents with its Falcon 9 rocket in less
than two years. A report released Friday
suggested the company has gone from being moderately profitable to
sustaining significant losses in the wake of those accidents. So now the
company must begin flying its workhorse Falcon 9 rocket safely, and
often. That effort starts Saturday.